A typical application for drum filters is to filter washer liquid at the rinse and wash stage of a phosphate line in an automotive assembly plant. Such drum filters generally comprise a perforate drum which is covered on the outside with a filter media for the filtration of liquid which flows from the outside of the drum to the inside of the drum. Discharge of liquid from the inside of the drum is effected by passing the liquid through the center of a tubular discharge shaft. Clean filter media is stored on a separate roll that is supported on a shaft that is substantially parallel to the shaft of the drum. The clean filter media generally comprises non-woven fibers such as Dacron, nylon, Orlon, etc. While generally satisfactory, such known drum filters have heretofore been faced with the problem of drift of the filter media longitudinally of the drum due to axial walking thereof.